Apparatus for generating pulse-modulated signal

Abstract

An apparatus for generating a pulse modulated signal having pulses corresponding to binary values of pixels of image data includes a modulation-data generating unit configured to generate modulation data in response to pixel control data and the image data, the modulation data including a predetermined number of bits for a pixel of the image data, wherein consecutive bits having bit positions responsive to the pixel control data in a line of the predetermined number of bits have a value responsive to a binary value of the pixel, and a modulated-signal generating unit configured to generate a pulse modulated signal in response to the modulation data.

1 . An apparatus for generating a pulse modulated signal having pulses corresponding to binary values of pixels of image data, comprising: 
 a modulation-data generating unit configured to generate modulation data in response to pixel control data and the image data, the modulation data including a predetermined number of bits for a pixel of the image data, wherein consecutive bits having bit positions responsive to the pixel control data in a line of the predetermined number of bits have a value responsive to a binary value of the pixel; and    a modulated-signal generating unit configured to generate a pulse modulated signal in response to the modulation data.    
   
   
       2 . The apparatus as claimed in  claim 1 , wherein the modulation-data generating unit includes a pixel-data holding unit configured to store data of the predetermined number of bits separately for each of a plurality of bit patterns, and wherein one of the plurality of bit patterns is selected as the predetermined number of bits for the pixel.  
   
   
       3 . The apparatus as claimed in  claim 1 , wherein the modulation-data generating unit is configured to select a portion of fixed-bit-pattern data in response to the pixel control data, the portion selected from the fixed-bit pattern data being the predetermined number of bits for the pixel.  
   
   
       4 . The apparatus as claimed in  claim 1 , wherein the modulation-data generating unit includes: 
 a first pixel-data generating unit configured to generate first pixel data having the predetermined number of bits, the first pixel data including a first fixed number of bits whose bit positions are responsive to current pixel control data;    a second pixel-data generating unit configured to generate second pixel data having the predetermined number of bits, the second pixel data including a second fixed number of bits whose bit positions are responsive to preceding pixel control data; and    a pixel-data merging unit configured to merge the first pixel data and the second pixel data so as to generate the modulation data.    
   
   
       5 . The apparatus as claimed in  claim 4 , wherein the first pixel-data generating unit is configured to store data of the predetermined number of bits separately for each of a plurality of bit patterns, and wherein one of the plurality of bit patterns is selected as the first pixel data.  
   
   
       6 . The apparatus as claimed in  claim 4 , wherein the second pixel-data generating unit is configured to store data of the predetermined number of bits separately for each of a plurality of bit patterns, and wherein one of the plurality of bit patterns is selected as the second pixel data.  
   
   
       7 . The apparatus as claimed in  claim 4 , wherein the first pixel-data generating unit is configured to select a portion of fixed-bit-pattern data in response to the current pixel control data, the portion selected from the fixed-bit pattern data being the first pixel data.  
   
   
       8 . The apparatus as claimed in  claim 4 , wherein the second pixel-data generating unit is configured to select a portion of fixed-bit-pattern data in response to the previous pixel control data, the portion selected from the fixed-bit pattern data being the second pixel data.  
   
   
       9 . The apparatus as claimed in  claim 1 , further comprising a high-frequency-clock generating unit configured to generate a plurality of high-frequency clock signals with respective, different phases, the high-frequency clock signals having a frequency higher than a pixel clock with which the pulse-modulated signal is synchronized.  
   
   
       10 . The apparatus as claimed in  claim 1 , wherein the modulation-data generating unit includes a circuit configured to indicate the bit positions of the consecutive bits, the circuit having a state thereof changed in response to the pixel control data.  
   
   
       11 . The apparatus as claimed in  claim 10 , wherein the predetermined number is temporarily changed when the circuit is reset.  
   
   
       12 . An optical scan apparatus, comprising the apparatus of  claim 1 .  
   
   
       13 . An image forming apparatus, comprising the optical scan apparatus of  claim 12.